1. Field of the Invention
The present invention relates generally to propulsion systems for vertical and short takeoff and landing (V/STOL) aircraft. More particularly, the invention relates to mechanisms for vectoring or directing the flow of exhaust from such propulsion systems.
2. Description of the Related Art
A class of V/STOL aircraft use lift fans or lift engines to generate the thrust needed to cause the aircraft to take-off vertically as well as to move laterally through the air. The exhaust gases from the lift fans are directed, or vectored, in various directions in order to move the aircraft laterally and longitudinally.
One method of directing exhaust flow requires the use of louvers that can be moved to direct the air flow forwardly or rearwardly away from the lift fan. Such an arrangement is described in U.S. Pat. No. 5,312,069. However, as louvers are moved, they tend to obscure or close off part of the exhaust area. This is disadvantageous as it will tend to cause a loss of thrust power.
Another approach is to use a ball and socket joint to provide flow deflection. If ball and socket joints are used for movement of a nozzle, the joints are subject to wear at the points where the joint attaches to the socket. Further, such joints may not seal properly leading to loss of thrust.
The present invention provides a novel mechanism and methods for directing the flow of exhaust gases associated with a V/STOL aircraft. In a preferred embodiment, the mechanism includes a pair of constant area nozzles associated with a plenum chamber that receives and contains exhaust gases. The nozzles are independently rotatable within circular exhaust openings in the plenum chamber to direct exhaust exiting from the plenum chamber in preselected directions such as vertically downward or directions forward or aft of the vertical plane.